This invention relates to an improved method and means for treating raw liquid waste, such as sewage.
One of the present day techniques for treating liquid wastes such as sewage which comprises water, contaminated by organic and inorganic matter which is dissolved in the water as well as organic and inorganic matter which is suspended in the water, is to mix a material, such as activated carbon or activated carbon and ash with the raw sewage in a contactor and the mixture is then transferred to a settling tank to permit adsorption of the dissolved polluting material and settling of the suspended polluting material. The suspended matter, which settles to the bottom of the settling tank, is called sludge, and contains sewage carbon. The sludge is transferred to a filter where it is de-watered and the cakes of dried sludge are then transferred to a pyrolyzing oven where the sewage carbon is converted to elemental carbon which is activated. The output of the pyrolyzer, comprising activated carbon and ash is dumped into the contactor to be mixed with the incoming sewage.
It has been found that the system described does not produce enough activated carbon to make the system self-sustaining. Consequently it has been necessary to provide commercial activated carbon to make up the deficiency. However, it has been found that commercial carbon required for this purpose is quite expensive.